The objectives of this subproject are (1) examine possible genetic factors underlying individual differences in susceptibility to drug addiction and chemical dependency (2) establish a bank of both DNA samples and cell lines from individuals actively or formerly addicted to heroin, cocaine, alcohol, and other abused drugs as well as from a group of normal control volunteers and (3) learn whether genetic or inherited differences in the endogenous opioid system, as well as other related systems, might cause an individual to be predisposed to addictive diseases.